Conventional gravity separators use an inclined perforated separator deck, which is vibrated in combination with an air flow directed vertically upwards through the separator deck to separate material into fractions or sections by weight. The inlet end of the deck is elevated with respect to the outlet end to define an end raise; and a first side of the deck is elevated with respect to a second side to define a side tilt. The air flow creats stratified layers, the lightest material being on top of the bed and the most dense material collecting on the bottom of the bed; and the deck vibration or agitation conveys the denser material up hill. The lighter material does not touch the deck surface and floats down hill thus, the vertically stratified bed of material is converted into a horizontally separated bed.
In order to control the rate at which the material flows over the deck, the end raise of the deck is adjusted. Also, to control the rate at which the heavier material is conveyed up hill, the side tilt or slope angle of the deck in the same plane as the direction of agitation is adjusted. One prior art technique for adjusting the end raise and side tilt in a gravity separator is shown in Steele U.S. Pat. No. 2,759,605, wherein two screw jacks are used to accomplish these adjustments. A major disadvantage with this type of adjustment assembly is the need to release and secure clamps before and after adjustments are made so that the machine must be stopped in order to allow the operator to make any adjustments. This can be both time consuming and costly since any down-time takes away from productive separating time.
Some prior art commercial gravity separators have end raise and tilt adjustment assemblies which can be changed while the machine is running. However, there is still a disadvantage to this type of adjustment assembly since it also requires the release and securement of clamps. Thus, when the machine is run during adjustment the loosening and tightening of the adjustment clamps reduces the quality of separation.
Conventional gravity separators used for seed separation have located the feeder to the deck at the low side of the deck. This, however, causes build up of material at the low side when the material is fed at a high rate. An artificial slope is thus formed by the material which is opposite to the slope of the deck, thereby working against separation. Such location of the feeder not only causes longer separation time, but also necessitates a longer deck.